SA 12V Conversion Question

I just bought a Denso 1-Wire Mini Alternator and want to convert my 1949 SA from a 6 Volt positive ground system to a 12 Volt negative ground system. In order to accomplish this I need a wiring diagram for the 12V setup. Anyone have one. The 6V system is a magneto ignition system with the battery servicing the starter and lights. The generator has a cutout relay mounted on top if that adds to the clarity of the conversion wiring. Also, does it matter if the lead to the starter is from the positive terminal of the battery rather than the negative terminal as currently wired?

Thanks for the help.
 
there is so much information and diagrams on this topic about installing alternators in place of 6 volt generators. just need to look it up here. and yes the alternator will be negative ground so positive to starter. myself I don't change 6 volt stuff to 12 volt on the 6 volt starters.
 
1 Do a search for Bob M Farmall diagrams

2. Remove generator and cutout
Isolate or remove the F wire from light switch to the generator F
Reverse ammeter connections
Install alternator with BAT wire from cutout connected to alternator output
Install 12 volt bulbs in the lights
Connect battery negative to ground, positive to starter switch/solenoid

Starter turns same direction either polarity. Magneto has no connection to battery system
 
Thanks for the clear concise explanation of the steps needed to revise the wiring. The knowledge freely given on this website is amazing, and truly appreciated.
 
Here is how I do it. First,take wire cutters and COMPLETELY strip out the old harness. Then install alternator. Run one wire from alt to amp gauge. then from gauge to battery.Done.A mag has absolutely NOTHING to do with charging system. One wire from mag to on/off switch.If you have a point system,pull power from amp gage to ignition switch. then to coil.Done.Wrap the whole thing with black tape in a neat clean sanitary harness.If you want lights,again pull power from amp gage to light switch,then to lights.The whole thing is so simple and easy.I've done at least 6 tractors as such. The first 20 years ago. Have never had a bit of problem with any.If you want,call me. I'd be glad to talk you through it. nine7zero-four 1 seven-1178
 
Also,an 'idiot' light is not needed. And you need to run a ground wire from the alternator to the engine block. Somehow,just grounding through the mounting bracket doesn't seem to work right.I just use a simple common onewire Delco. available from NAPA for under 60 bucks.Just did an 8N ford a month ago. Works perfect.
 
I have the alternator installed and have disconnected the F terminal wiring and reversed the ammeter wiring as you outlined. One question before I energize the system. The light switch on my SA is a 4-position switch...Low charge, High charge, Dim light and Bright light. The Steiner catalog, Part No. IHS1636 shows this switch for use with a cut-out relay charging system. The wire from the cutout relay F terminal which is no longer in use is connected to the light switch at a terminal that looks like one end of a brass bar wrapped with a coil. Can I still use this switch or do I need to get a different one. I don't want to energize the system and burn it up. Your advice will be appreciated.
 

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